Memory devices are typically provided as internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including volatile and non-volatile memory. Volatile memory can require power to maintain its data and includes random-access memory (RAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM), among others. Non-volatile memory can provide persistent data by retaining stored data when not powered and can include NAND flash memory, NOR flash memory, phase change random access memory (PCRAM), resistive random access memory (RRAM), and magnetic random access memory (MRAM), among others.
Memory devices can be combined together to form a solid state drive (SSD). An SSD can include non-volatile memory, e.g., NAND flash memory and/or NOR flash memory, and/or can include volatile memory, e.g., DRAM and/or SRAM, among various other types of non-volatile and volatile memory. Flash memory devices can include memory cells storing information in a charge storage structure such as a floating gate, for instance, and may be utilized as non-volatile memory for a wide range of electronic applications.
Memory is utilized as volatile and non-volatile data storage for a wide range of electronic applications. Non-volatile memory may be used in, for example, personal computers, portable memory sticks, digital cameras, cellular telephones, portable music players such as MP3 players, movie players, and other electronic devices. Memory cells can be arranged into arrays, with the arrays being used in memory devices.
A hard read is a read operation to distinguish between the multiple states to which a memory cell may be programmed. A hard read returns hard data, e.g., a digit corresponding to the state determined by the read operation. Soft data can be data other than hard data. Soft data can indicate (or be used to indicate) a confidence level regarding confidence associated with the hard data. For example, a soft read can be used to determine the particular voltage to which a memory cell is charged, which can be used to characterize the reliability of the hard data. The reliability of hard data may be less for a memory cell charged to a particular voltage near a boundary between two states, than for a memory cell charged to a particular voltage near the center of a voltage range corresponding to a state. Various error-correcting code schemes can perform much better using soft data. However, soft data determined by a soft read is slower compared to a hard read, and communicating soft data determined by a soft read can consume bandwidth and impact memory throughput.